Until last week, no study had ever been published that tested period products—tampons, pads, discs, cups, and underwear—using human blood. A team of four women just changed that. On August 7, Dr. Bethany Samuelson Bannow and a group at Oregon Health & Science University in Portland released a study to test saturation and capacity levels in menstrual products in hopes of better understanding how to diagnose heavy menstrual bleeding, or HMB, which impacts millions of Americans. Why had it taken so long to test a product made to contain human blood with human blood?